Stark Effects

The potential drop across the Helmholtz layer (the dense part of the DL) typically ranges from 0.1 to 1 V, and because this occurs across a very short distauce 

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Not only can electronic wavefiinctions tell us about the average values of all the physical properties for any particular state (i.e. above), but they also allow us to tell us how a specific perturbation (e.g. an electric field in the Stark effect, a magnetic field in the Zeeman effect and light s electromagnetic fields in spectroscopy) can alter the specific state of interest. For example, the perturbation arising from the electric field of a photon interacting with the electrons in a molecule is given within die so-called electric dipole approximation [12] by ... 

A MBER spectrometer is shown schematically in figure C1.3.1. The teclmique relies on using two inhomogeneous electric fields, the A and B fields, to focus the beam. Since the Stark effect is different for different rotational states, the A and B fields can be set up so that a particular rotational state (with a positive Stark effect) is focused onto the detector. In MBER spectroscopy, the molecular beam is irradiated with microwave or radiofrequency radiation in the... 

Wild U P, Guttler F, Pirotta M and Renn A 1992 Single molecule spectroscopy stark effect of pentacene in p-terphenyl Chem. Phys. Lett. 193 451-5... 

Orrit M, Bernard J, Zumbusch A and Personov R I 1992 Stark effect on single molecules in a polymer matrix Chem. Phys. Lett. 196 595-600... 

Tamarat P, Lounis B, Bernard J, Orrit M, Kummer S, Kettner R, Mais S and Basche T 1995 Pump-probe experiments with a single molecule ac-Stark effect and nonlinear optical response Phys. Rev. Lett. 75 1514-17... 

Empedocles S A and Bawendi M G 1997 Quantum-confined Stark effect in single CdSe nanocrystalline quantum dots Science 278 2114-17... 

The orientation of the dipole moment, experimentally established by the Stark effect (158), can also be compared to the calculated ones (Fig. 1-5). 

Stark effect in diatomic, linear and symmetric rotor molecules... 

Using the Stark effect, the dipole moment of, for example, CH3F has been found to be... 

Dipole moments of asymmetric rotors or, strictly, their components along the various inertial axes, may be determined using the Stark effect. 

From accurate measurements of the Stark effect when electrostatic fields are applied, information regarding the electron distribution is obtained. Further Information on this point is obtained from nuclear quadrupole coupling effects and Zeeman effects (74PMH(6)53). 

Microwave spectroscopy (Stark effect). d, the probable approximate angle between the direction of fj, and the symmetry (or near symmetry) axis of the ring through atom N-1, in the molecular plane, has the value 69°. 

Diels-Alder reactions, 1, 618 reactions, 1, 617-620 synthesis, 1, 614-616 Stark effect... 

Atomic charges (q ) Dipole moments [57] QM, dielectric permittivity, Stark effect, microwave... 

These can be determined experimentally to very high accuracy from the Stark effect and molecular beam studies. The experimental accuracy is far beyond the capabilities of ab initio studies. At the other extreme, the original route to these quantities was through studies of the dielectric polarization of species in solution, and there is currently interest in collision-induced dipole moments. In either case, the quantities deduced depend critically on the model used to interpret the experiment. 

Some of these difficulties can be circumvented. In particular a cavity-type Stark effect spectrograph has been built which seems capable of yielding relative intensities of near-by lines to within two or three per cent.32 Barrier values for acetaldehyde and fluoro-ethane have been obtained which are in excellent agreement with those from the frequency method described below. From Eq. (1) it can be seen that the error in v is... 

Spin orbitals, 258, 277, 279 Square well potential, in calculation of thermodynamic quantities of clathrates, 33 Stability of clathrates, 18 Stark effect, 378 Stark patterns, 377 Statistical mechanics base, clathrates, 5 Statistical model of solutions, 134 Statistical theory for clathrates, 10 Steam + quartz system, 99 Stereoregular polymers, 165 Stereospecificity, 166, 169 Steric hindrance, 376, 391 Steric repulsion, 75, 389, 390 Styrene methyl methacrylate polymer, 150... 

A simple consideration involving a slow mechanical transformation shows that if the energy quantity corresponding to the second-order Stark effect of a system is... 

Jones, 1 Roy. Soo. Proc., A, vol. 105, p. 650 (1924). The first attempt to calculate the mole refraction from the quadratic Stark effect formula was made by Lennard-Jones (Jones), with the old quantum theory, f Z. f. Physik, vol. 38, p. 518 (1926). 

Stark effect of a hydrogen-like atom, using the Schrodinger wave mechanics. Their equation, obtained independently and by different methods, is... 

As early as 1927 this problem had been attacked by Wang,4 using the method developed by Epstein5 for the treatment of the Stark effect. 

In EMIRS and SNIFTIRS measurements the "inactive" s-polarlsed radiation is prevented from reaching the detector and the relative intensities of the vibrational bands observed in the spectra from the remaining p-polarised radiation are used to deduce the orientation of adsorbed molecules. It should be pointed out, however, that vibrational coupling to adsorbate/adsorbent charge transfer (11) and also w electrochemically activated Stark effect (7,12,13) can lead to apparent violations of the surface selection rule which can invalidate simple deductions of orientation. 

Thus the IR active modes will be determined by the matrix elements of the polarlsablllty matrix and not by a combination of the surface selection rule and the normal IR selection rules l.e. all of the Raman active modes could become accessible. This effect has been formalized and Its significance assessed In a discussion (12) which compares Its magnitude for a number of different molecules. In the case of acrylonitrile adsorption discussed In the previous section, the Intensity of the C=N stretch band appears to vary with the square of the electric field strength as expected for the Stark effect mechanism. 

The foundation of our approach is the analytic calculations of the perturbed wave-functions for a hydrogenic atom in the presence of a constant and uniform electric field. The resolution into parabolic coordinates is derived from the early quantum calculation of the Stark effect (29). Let us recall that for an atom, in a given Stark eigenstate, we have ... 

In addition to the photoluminescence red shifts, broadening of photoluminescence spectra and decrease in the photoluminescence quantum efficiency are reported with increasing temperature. The spectral broadening is due to scattering by coupling of excitons with acoustic and LO phonons [22]. The decrease in the photoluminescence quantum efficiency is due to non-radiative relaxation from the thermally activated state. The Stark effect also produces photoluminescence spectral shifts in CdSe quantum dots [23]. Large red shifts up to 75 meV are reported in the photoluminescence spectra of CdSe quantum dots under an applied electric field of 350 kVcm . Here, the applied electric field decreases or cancels a component in the excited state dipole that is parallel to the applied field the excited state dipole is contributed by the charge carriers present on the surface of the quantum dots. 

Empedocles, S. A. and Bawendi, M. G. (1997) Quantum-confined stark effect in single CdSe nanocrystallite quantum dots. Science, 278, 2114-2117. 

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